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71.
Yuxiang Mo Sitaram Aryal Paul Rulis Wai‐Yim Ching 《Journal of the American Ceramic Society》2014,97(8):2646-2653
The term “MAX phase” refers to a very interesting and important class of layered ternary transition‐metal carbides and nitrides with a novel combination of both metal and ceramic‐like properties that have made these materials highly regarded candidates for numerous technological and engineering applications. Using (Cr2Hf)2Al3C3 as an example, we demonstrate the possibility of incorporating more types of elements into a MAX phase while maintaining the crystallinity, instead of creating solid solution phases. The crystal structure and elastic properties of MAX phase‐like (Cr2Hf)2Al3C3 are studied using the Vienna ab initio Simulation Package. Unlike MAX phases with a hexagonal symmetry (P63/mmc, #194), (Cr2Hf)2Al3C3 crystallizes in the monoclinic space group of P21/m (#11) with lattice parameters of a = 5.1739 Å, b = 5.1974 Å, c = 12.8019 Å; α = β = 90°, γ = 119.8509°. Its structure is found to be energetically much more favorable with an energy (per formula unit) of ?102.11 eV, significantly lower than those of the allotropic segregation (?100.05 eV) and solid solution (?100.13 eV) phases. Calculations using a stress versus strain approach and the VRH approximation for polycrystals also show that (Cr2Hf)2Al3C3 has outstanding elastic moduli. 相似文献
72.
Yin‐Ching Chan Cheng‐Kuang Hsu Ming‐Fu Wang Jiunn‐Wang Liao Ting‐Ya Su 《Journal of the science of food and agriculture》2006,86(10):1517-1525
This study was designed to evaluate the effect of yam tuber material [Dioscorea alata L. var. purpurea (M.) Pouch.] on the amyloid β‐protein (Aβ) accumulation, monoamine oxidase (MAO) activity, cognitive ability and antioxidative defense system in senescence‐accelerated mice (SAMP8). Three‐month‐old male mice were fed with four different diets for 12 weeks: a casein diet (control group) and a casein diet supplemented with either 100, 200 or 400 g kg?1 lyophilized yam. The results of the active shuttle avoidance test showed that the mice fed with the yam‐containing diets had significantly better learning and memory ability than the control group. All yam‐containing diet groups had lower Aβ levels and MAO B activities than the control, whereas the MAO A activity did not differ among the four diet groups. At the 400 g kg?1 level, the yam‐containing diet group showed significantly lower concentration of thiobarbituric acid‐reactive substances (TBARS), higher total thiol level and superoxide dismutase (SOD) activity in the hippocampus than the control, but these values were not altered by the 100 and 200 g kg?1 yam‐containing diet groups. The addition of 200 or 400 g kg?1 yam also lowered the triglyceride levels but not the total cholesterol concentration. These results indicate that lyophilized yam could reduce brain Aβ accumulation, MAO B activity and cognitive deficits and promote the antioxidative defense system in SAMP8 mice. The improvements were in a dose‐dependent manner, possibly because the 400 g kg?1 yam‐containing diet might contain more antioxidative phytochemicals. Copyright © 2006 Society of Chemical Industry 相似文献
73.
Sesame exhibits many beneficial physiological effects, which are mostly related to its lignan compounds, such as sesaminol glucosides. This investigation studies the distribution and elimination of sesaminol triglucoside from sesame in Sprague Dawley (SD) rats. In order to investigate the distribution of sesaminol triglucoside (p.o. 500 mg/kg) in SD rats, the changes in concentration of sesaminol triglucoside and its metabolites were determined in tissues and plasma within 24 h period after tube‐feeding to SD rats. Results showed that sesaminol triglucoside may be deglycosylated to form sesaminol first by intestinal microflora and then incorporated via lymphatic absorption into the cardiovascular system, transported to other tissues. The concentrations of sesaminol triglucoside and its metabolites in rectum, caecum, colon, and small intestines are higher than those in liver, lung, kidney, and heart. Its concentration in brain is low but detectable. Glucuronidation and sulfation was the main metabolic pathway for sesaminol in urine, and fecal elimination was a major route of elimination. From LC/MS/MS analysis of rat organs, sesaminol triglucoside can be converted to mammalian lignans, enterodiol (END), and enterolactone (ENL), by rat intestinal microflora. In the plasma, concentrations of END and ENL were 5.9 ± 0.2 and 5.5 ± 0.2 μmol/mL, respectively. 相似文献
74.
Ching W. Chan Benjamin J. Deadman Merilyn Manley-Harris Alistair L. Wilkins Dagmar G. Alber Elizabeth Harry 《Food chemistry》2013
The flavonoid components of New Zealand mānuka (Leptospermum scoparium) honey have been quantified in a series of 31 honeys of varying non-peroxide antibacterial activity to clarify discrepancies between previous studies reported in the literature. Total flavonoid content was 1.16 mg/100 g honey. The principal flavonoids present were pinobanksin, pinocembrin, luteolin and chrysin and together these represented 61% of the total flavonoid content. 1, 2-formyl-5-(2-methoxyphenyl)-pyrrole, which was weakly correlated with the non-peroxide antibacterial activity, was isolated from the flavonoid fraction and separately synthesised. 1 did not display inhibitory activity against Staphylococcus aureus in vitro and thus the origin of the correlation, which is still unknown, is not a direct contribution. 相似文献
75.
Chen CH Liu TZ Chen CH Wong CH Chen CH Lu FJ Chen SC 《Molecular nutrition & food research》2007,51(8):962-968
There is increasing evidence that reactive oxygen species (ROS) are intimately involved in the oxidative damage of tissues for a wide variety of pulmonary diseases. Thus, it is desirable to search for chemopreventive agents that can counteract ROS-mediated injury to the pulmonary tissues. Using a human lung fibroblast IMR-90 cells as the experimental model, we first demonstrated that nearly 90% of intracellular ROS could be removed when H(2)O(2)-treated cells (200 microM) simultaneously incubated with 10 microg/mL of tannic acid (TA), gallic acid (GA), ellagic acid (EA), and propyl gallate (PA). Using C(11)-BODIPY(581/591 )as a lipid peroxidation probe, we also attested that all these compounds examined (10 microg/mL) could alleviate H(2)O(2)-evoked lipid peroxidation phenomena. Next, we examined the protective effects of these compounds on the depletion of intracellular glutathione (iGSH) in H(2)O(2)-treated cells using CMF-DA probe. Interestingly, PA was demonstrated to be the only compound that could effectively protect the integrity of iGSH from being depleted by this system. Finally, the protective effects of these compounds against oxidative DNA damage were evaluated using 8-oxoguanine formation as a marker. Our data indicated that all four compounds suppressed the formation of 8-oxoguanine effectively. Taken together, our data suggested that TA, GA, EA, and PA can protect cells from oxidative stress. 相似文献
76.
Feng‐Yao Tang Yu‐Ching Su Nai‐Chia Chen Hui‐Shan Hsieh Kaun‐Suei Chen 《Molecular nutrition & food research》2008,52(6):683-691
Metastasis is the primary cause of death from breast cancer. Cell migration and invasion play important roles in neoplastic metastasis. The insulin‐like growth factor (IGF‐1) stimulates cell migration through activation of PI‐3K/Akt signaling pathway. IGF‐1 induces the tumorigenicity of many types of cancer cells and is critical for metastatic cell spread in estrogen receptor (ER)‐negative breast‐cancer cells. Matrix metalloproteinase‐2 (MMP‐2) is a key enzyme in the degradation of extracellular matrices and its expression has been dysregulated in breast cancer invasion and metastasis. Resveratrol exhibited potential anticarcinogenic activities in several studies. However, the inhibitory effects of resveratrol on the expression of MMP‐2, migration and invasion of breast‐cancer cell have not been demonstrated yet. In the present study, we investigated the anti‐invasive mechanism of resveratrol in human breast cancer MDA‐MB 435cells. Here, we showed that IGF‐1 is a potent stimulant of the migration of ER‐negative human breast‐cancer cells. Resveratrol could inhibit IGF‐1‐mediated cell migration of MDA‐MB 435 in vitro. The inhibitory effect of resveratrol was mediated in part through the suppression of the activation of PI‐3K/Akt signaling pathway. Furthermore, IGF‐1‐mediated expression of MMP‐2 was significantly inhibited by resveratrol in concomitance with alteration of cell invasion. 相似文献
77.
Hsiao‐ling Chen Ling‐tiao Hong Jong Kang Lee Ching‐jang Huang 《Journal of the science of food and agriculture》2009,89(3):517-522
BACKGROUND: Yam products have been marketed for treating postmenopausal syndromes. This study investigated the effects of Dioscorea alata L. cv. Tainung No. 2 (TNG yam) on the bone density of ovariectomised (OVX) female BALB/c mice and the mechanism whereby TNG yam exerted this effect. Sham and OVX control groups were fed a control diet while remaining OVX mice were randomly allocated into experimental diets, i.e. yam (630 g TNG powder kg?1), E2 (20 mg 17β‐oestradiol kg?1), or genistein (2 g genistein kg?1) diet. After 12 weeks of feeding, the uterine weight, indices of bone mass and caecal short chain fatty acids were determined. RESULTS: Neither a yam nor genistein diet restored the OVX‐induced uterine atrophy as did the E2 diet. The femoral and lumbar bone mineral density (BMD) of mice fed the yam diet was greater than those of the sham group, respectively (P < 0.05 vs OVX control), while the lumbar BMD of yam and sham groups were similar (P > 0.05 vs sham). The femoral ash and calcium content in the yam group was significantly greater than that in the OVX control group, respectively (P < 0.05 vs OVX control). The total short chain fatty acid content in the caecum, only enhanced in the yam group, was not correlated with the calcium content of either bone or the plasma calcium level. CONCLUSION: TNG yam prevented loss of BMD and improved bone calcium status without stimulating uterine hypertrophy in OVX BALB/c mice. TNG yam may be beneficial for postmenopausal women for preventing bone loss. Copyright © 2008 Society of Chemical Industry 相似文献
78.
Membrane distillation (MD) is a membrane separation process that has long been investigated in small scale laboratory studies and has the potential to become a viable tool for water desalination. MD is a separation process that combines simultaneous mass and heat transfer through a hydrophobic microporous membrane. A solar collector is used in direct contact membrane distillation (DCMD) to heat seawater as a temperature driving force in heat transfer to establish seawater desalting systems. The effect of the temperature difference makes the brine vaporize in the hot fluid side and condense in the cold fluid side. The optimal operating parameters on the pure water production rate will also be examined in this study. The purposes of this study are to develop the theoretical heat and mass transfer formulations, simulate heat transfer rate of solar collector with internal fins in membrane distillation, and investigate the mass‐transfer efficiency improvement in membrane distillation with the brine flow rate, solar collector efficiency, and temperature difference between both sides of membrane as parameters. © 2007 Wiley Periodicals, Inc. Heat Trans Asian Res, 36(7): 417–428, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/htj.20172 相似文献
79.
Well-aligned anodic tungsten oxide (WO3) nanotubes with lengths approaching 600 nm was successfully synthesised via electrochemical anodisation of tungsten (W) film at 40 V in a bath with electrolyte (pH 3) consisted of 1 M of sodium sulphate (Na2SO4) and 0.7 wt-% ammonium fluoride (NH4F) for 15 min. It was found that the production of dense compact oxide layer on pure W film could be explained with high concentration of H+ ions accelerated the hydrolysis ability on the W surface to form thick WO3 layer under acidic condition (pH: 3). The photocatalytic activity performance was increased by ≈15% for the dense WO3 nanostructures film as compared to the thin and irregular WO3 nanostructures film because of the high active surface area to absorb more photons from solar irradiation for triggering the charge carriers separation and then improvement of internal and external diffusion of the reactants. 相似文献
80.
Bin Tian Robert J. Sclabassi Jennting T. Hsu Qiang Liu Ching Chung Li Mingui Sun 《电子科学学刊(英文版)》2007,24(5):642-648
Research interest in multi-frame Superresolution has risen substantially in recent years.This paper presents a modified Projection Onto Convex Set (POCS) superresolution method based on wavelet transform.The method analyzes the image formation model from wavelet multiresolution analysis point of view and defines an closed convex set and its corresponding projection based on wavelet transform.An iterative procedure is utilized to reduce the estimated errors of the result image,and this guarantees the estimated image to lay in the intersection of different convex sets,thus produces a high resolution image with a reduced error.The effectiveness of the algorithm is demonstrated by experimental results. 相似文献